Not only is Firefox for your desktop now 25%* faster (*based on the data we’ve compiled from testing), it’s also 100%* better looking (*based on just our eyeballs)!
Mac fans will especially love the much-requested support for the high-definition Retina display. All those movies you download will look more awesome in Firefox. And high-def game playing? Wowza. High-def Web browsing? The Internet never looked so good. Look at the difference!
If you’re on a recent version of Firefox, you’ll be automatically upgraded. But if you have auto updates turned off or haven’t seen an update yet, here’s how to take control of those updates!
Source: Firefox Blog